This invention relates to a method for lining existing pipelines such as water conduits and sewers disposed in the ground with a flexible hose containing a curable plastic material which is introduced in its uncured state into the conduit to be lined and is then made stable in form by curing of the curable plastic material included in the hose.
For repair of pipelines broken or damaged in another way and/or weakened by corrosion dug down into the ground, e.g. water conduits and sewers, it has previously been necessary to dig up the damaged portion of the pipeline to be able to repair the line by replacing the damaged portion by a new piece of pipe. As this procedure is uncomfortable, time-consuming, requires much equipment and is costly, attempts have been made for ten years or so to create simpler and more efficient methods for repair of existing pipelines disposed in the ground which methods do not require digging or another external uncovering of the pipeline or the portion thereof that must be repaired. Thus, at present there are various restoration methods such as cement injection which, however, are best suited for naturally sloping conduits with occasional big places of leakage but the condition of which is otherwise good, panel lining and installation of a new conduit in the existing conduit, which latter methods, however, involve a substantial reduction of the conduit area and are therefore only suitable for big conduits, the capacity of which is not fully utilized.
However, these known restoration methods can only be used to a limited extent, and therefore attempts have also been made to develop a restoration method, the principle of which is soaking a terylene felt shaped to a pipe with a polyester compound and then introducing this as a laminate in uncured state into the pipeline to be restored by means of a pressure medium such as water or air. When the laminate has been positioned within the pipeline hot water or hot air is pumped in under pressure to cure the polyester in the laminate while the laminate is kept expanded against the surrounding pipeline so that the laminate forms a tight inner surface layer within the pipeline after curing. This type of restoration method has been found to have certain advantages but despite a development work of several years one has not been successful in mastering the problem of the very curing of the laminate which has turned out to be very troublesome, not least considering the cooling influence, especially in winter-time, that the surrounding pipeline and the masses of earth around the latter as well as in-flowing cold ground water or surface water has on the plastic during its curing. With the curing method used so far, i.e. with hot water or hot air which is circulated through the laminate applied within an existing pipeline it has also appeared to be very difficult to achieve a satisfactory curing along the whole pipeline and to check the curing process as well as the result thereof. The curing process will also take a relatively long time due to the constant cooling to which the hot water or hot air is exposed and, moreover, requires much energy.
It is therefore the object of this invention to provide a method of lining pipelines with a flexible curable plastic comprising a sock or hose which has not the above-mentioned shortcomings and deficiencies but makes possible a rapid and efficient curing of the plastic in the sock with a relatively slight consumption of energy. Moreover, it is the object of this invention to achieve a device for carrying out the method.